Shock absorber



Dec. 17, 1929. A, W F, MANZEL 1,740,429

SHOCK ABSORBER Filed DeG. 16. 1927 2 Sheets-Sheet l Dec. 17, 1929. A W, F, MANZEL 1,740,429

I SHOCK ABSORBER Filed DSG. 16, 192'? 2 Sheets-Sheet 2 Patented Dec. l?, 1929 UNITED STATES PATENT OFFICE ADOLPH W. F. MANZEL, OF BUFFALO, NEW YORK, ASSIGNOR TO MANZEL BROS. G0.,

OF BUFFALO, NEW YORK, A CORPORATION OF NEVI YORK SHOCK ABSORBER Application filed December 16, 1927.

My invention relates to shock absorbers for cushioning the movement of two relatively movable members, and more particularly to that type for use in automobiles or other vehicles, to check the rebound of the vehicle body when the vehicle passes into a rut or over a projection in the road.

The primary object of my invention is the production of a simple and inexpensive, yet highly elfective shock absorber of the type in which oil or other suitable fluid is ntilized in conjunction with suitable control means governing the flow or passage of the oil or other fluid under the principle involved in what is generally termed hydraulic shock absorbers.

Another object of my invention is to provide a shock absorber in which provision is made in an extremely simple manner, and with the use of exceedingly few parts, for more effectively resisting the shocks to which an automobile is subjected when passing over rough roacs; and to so control the flow of the resisting fluid within the shock absorber, that the vehicle body, when suddenly depressed in passing into a rut or over a projection in the road, will assume its normally sustained position by an upward or recovering movement which will be gradual and smooth and without marked resistance at any particular point in its recovering` movement.

Other objects are to simplify the control means within the shock absorber, whereby the resisting iiuid is controlled in its passage from one chamber into another; and to provide simple and effective regulating means whereby the normal resisting force may be varied, depending on the weight carried; thus making it possible to use the shock ab scrber, without change in construction or size, for automobiles of both light and heavy construction, within reasonable limits.

A further object of my invention is to simplify the control mechanism whereby the passage of oil from one part within the shock absorber to another, is more effectively controlled than has heretofore been possible.

A still further object of my invention is to provide means to prevent free play or ineffective action of the parts upon initial move- Serial No. 240,469.

ment of the piston under compressing action.

lith these and other objects in view, the invention consists in the novel features of construction, yand in the arrangement and combination of parts to be hereinafter described and more particularly pointed out in the subjoined claims.

ln the drawings Fig. l is a side elevation of my improved shock absorber as applied to an automobile; the rear end of the chassis of the automobile, one of its springs, and one of its axles being shown in connection therewith.

Fig. 2 is a section taken on line 2-2, Fig. l.

Fig. 3 is an edge view of the lower part of the shock absorber looking toward the right in Fig. 1.

Fig. 4 is an enlarged section taken on line 4 4, Fig. 2.

Fig. 5 is a transverse section taken on line 5 5, Fig. 4.

Fig. 6 is an enlarged horizontal section taken on line 6 6, Fig. 4.

F ig. 7 is a vertical section through the inner end of a shock absorber, showing a modified form of control device for controlling the flow of fluid from one part of the shock absorber casing to another.

Fig. 8 is a similar section, showing a further modified form of the invention.

Fig. 9 is a fragmentary sectional view showing a still further modified form of my invention.

Fig. l0 is an edge view of a packing disk used in said lastmentioned modified form.

Fig. l1 is a transverse section taken on line lll-ll, Fig. 4.

In Figs. l and 2 I have illustrated parts of an automobile to which one of my im! proved shock absorbers is shown applied, and as illustrated, these parts are at the front of the automobile. It is, however, to be unden stood that a shock absorber is provided at each side of the automobile or other vehicle, and that a pair of shock absorbers may be used at the front or at the rear, or both at the front and the rear of the automobile.

The reference numeral l0 designates the frame or chassis of an automobile, and ll one of the leaf springs fastened at opposite IMO ends to said frame or chassis in the usual manner. This leaf spring is secured between its ends to an axle 12, which is shown in cross section in Fig. 1, and in top plan view in Fig. 2.

When passing over a rut or obstruction in the road, the fleaf springs become liezzed and opposite ends thereof are forced more closely to the road surface under the spring pressure,

-Withthe-result that the body of the automo-l bile, connected lto vthe ends of the spring by means of the chassis members, is drawn downwardly. The tendency of the springs to recover after passing over the rough portion or portions of a road, will cause'a decided upthrow of thebody of the automobile, particularly when traveling at a high rate of speed, :and yit is `this upthrow of the body of the `automobile which is diilicult to control in an effective ymanner so that riding within an :automobile occurs with free and easy action of the vehicle body. The body or chassis and a spring or aXle of an automobile may be `considered as two relatively movable parts, to oneof which the housing creasing of the shock absorber is secured, and to the other an yelement extending from said housing or casing andadapted to actuate parts therein to cause the resisting fluid to move within the housing or casing under positive control. VThe housing or-casingof the shock absorber' is designated by the numeral 13 and it is` divided into two chambers 14, 15, by a wall 16. The chamber 15 is cylindrical in cross sectionandserves as a plunger cylinder. The chamber 14 may be of any desired formation incross section, and has controlled conduit c-onnection with the cylinder 15, as will ap- ;pear hereinafter.

Thel wall 16 has a portion cast thereon which projects into the lower portion of the chamber 14, and this projecting portion is hollowed out to form a valve chamber 17 which .has connection with the cylinder 15 through the medium of a passage 18, and Aalso connection with the bottoni of the chamber 14 by `providing la screw-threaded opening 19 in the bottom wall of said valve chamber and `thread-'ing thereinto a flanged sleeve 20fbeveled' at its inner end,as at 21, to provide 'a val-.ve seat. for a valve 22, preferably of spherical shape. Between the valve 27 and `vthe upper end wall of the valve chamber 17 a coil spring 23 is positioned, the lower end of said spring bearing against said valve and -the' upper end being seated in a Adepression 24 formed on the inner side of said top wall.

In the `bottom of the chamber 14 a screwn threaded opening 25 is provided into which is 'threaded a plug 26. This opening is alined with the screw-threaded opening 19 in the bottom of the valve chamber 17 and lis of suiicient size to permit the sleeve20, the ball valve 22, and the spring 23 to be entered into the valve chamber from the bottom of the casing.

Within theplunger cylinder 15, a piston i bearing against the under side of said piston or plunger, and the lower end against said bottom wall.

The body portion -of the housing or casing 13 is open at .its upper end and cover 29 is Aapplied thereto which is rendered fluid tight by means of a gasket or other suitable packing placed between it and the upper edge of said body portion, and it is securedV to said body portion by means of screws 31,

or in any other approved manner.

lt is to be noted that the wall 1G separating the plunger cylinder from the chamber 14, terminates at its upper end a distance from the upper end of the bod-y portion of said housing or casing, so that the chamber 14 is considerably widened at its upper end and extends over the top of the plunger cylinder 15, and more particularly over the piston or plunger 27. In the upper end of the widened portion of the chamber 14, a roel: shaft 32 is transversely disposed, one end of this rock shaft being jou-rnalec. in one of the side wal-ls of the casing, for example, in a boss 33 (see Fig. 2). This roclr shaft efrtends outwardly from the casing through a boss formed in the other side wall thereof, and preferably integral therewith is a crank or actuating` lever 35 disposed at a Aright angle thereto and substantially parallel with the side walls lof the casing, and also with the frame or chassis of the automobile. lf desired, this crank or actuating lever may be separately formed and secured to the proj-ecting end o-f the rock shaft. That portion of the rock shaft positioned between the two side walls of the casing 13 has an actuating arm 36 secured thereto, the outer end of which is `extended over the plunger orpiston 27 and is in Contact therewith. This outer end may be hardened or provided with a hardened portion which bears against the hardened upper end of the piston or plunger so that wear at this point is considerably minimized. Suitable connection is made between the outer end of the crank or actuating lever and the axle 12, and this connection, in the form shown, comprises a strip of webbing` or other flexible material 37 secured at one end to the free end of said crank or actuating lever 35 and its lother end tothe axle 12 in any approved manner. Y

The top or cover 29 of the easing is provided with a filling opening 38 through which oil or other suitable Huid to be used is to be poured into the casing, this lilling opening being closed with a screw plug 39.

In the edge wall ofi: the valve chamber 22 a screw-threaded opening 40 is provided into which is screw-threaded the reduced screwthreaded end 41 oin a sleeve or guide 42, said sleeve or guide projecting into the chamber 14 and terminating in close proximity to the adjacent edge wall oi' the casing. This sleeve or guide has a slot or elongated opening 48 formed therein which extends from the outer end thereof inwardly, as best shown in Fig. 6; the inner end of this elongated opening or slot terminating at the reduced screw-threaded port-ion of the sleeve or guide. In said edge wall of the casing, an opening` 44 is formed, the axis of which is coincident with that of the sleeve or guide 42, and the outer portion of this opening is screw-threaded to receive a gland 45 which is internally screw-threaded, and has threaded thereinto an adjusting screw 4G provided with a polygonal head to permit the application 'thereto of a wrench for adjusting the same. This head is also provided with a kerlI in its head so that it may be adjusted with a screw driver or other flat tool or object. The gland 45 is recessed at its outer end, as at 47, and threaded onto said adjusting screw is a lock nut 48 which is also recessed on its inner side, as at 49; the two recessed portions 47 and 49 forming an annular space in which packing 50 is placed, thus rendering the device fluidtight at this point.

117 ithin the bore olf the sleeve is slidably arranged a cylindrical control stem or valve 51, which is reduced at its outer end, as at 52, to 'form an outwardly-facing shoulder on said valve. On this reduced Outer end a stop collar 53 is mounted, it comprising a disk portion 54 which is adapted to lie against the end oi' the sleeve, and a boss 55 extending outward axially from said disk. The eX- tremity oi the reduced portion oi said control stem or valve is upset within a -depression in tl e end of said boss, as clearly shown in l-Tig. 6, thus serving to hold the collar securely to the stem or valve 51.

The adjusting screw 46 is bored out along its inner portion, as at 56, and a coil spring 57 has its outer portion disposed within the bore of said adjusting scr-ew and its inner portion extending inwardly therefrom in contact with the outer i'ace of the disk portion of the collar 53, the inner end oi' said spring surrounding the boss 55 oi' said collar and the outer end thereof bearing against the inner end wall of the bore Ac-rmed in said adjusting screw. By boring out the adjusting screw, a comparatively long and sensitive spring may be used without forming a very long projecting portion on the casing of the shock absorber, and the tension of this spring can be easily adjusted by loosening the lock nut 48 and rotating the adjusting screw 45 either to the right or leit. The rotation of the adjusting screw to the right, will result in increasing the tension of the spring, as indicate-d in Fig. 3, while rotation to the left will diminish the tension of the spring.

1t is to be noted that the inner end of the control stem or valve 51 terminates short of the inner end of the elongated opening or slot 43 formed in the sleeve or guide 42, which sleeve or guide may be termed the valve sleeve, and that the collar 53 bears against the outer end of the sleeve to limit the inward movement of said valve and govern the degree to which the elongated opening or slot 43 is left open. v

When using the shock absorber, it is supplied with oil or some other fluid, the oil preferably reaching to the top of the dividing wall 16. 1t, how-ever, will be quite apparent that the device will operate successi'ully with the level oi the oil in the plane of the under side o the piston 27, or at any level thereabove.

lVhen the automobile travels over uneven roads, passes over ruts, or strikes obstructions, the chassis and body of the automobile will lower, due to its being supported by th-e springs 11, which become flexed, and cause the casing 13 of the device to move downwardly with the body of the' automobile. Under this action the crank or actuating lever 35 assumes an inclined position, which results in the actuating arm 36 more closely approaching the cover 29 of the casing. This allows the spring 28 in the cylinder 15 to force the plunger or piston 27 upwardly within said cylinder, thereby creating suction within the lower portion of the cylinder and the valve chamber and causing the spherical or ball valve 22 to be lifted from the valve seat 21 against the action oli' the spring 23. This results in oil being drawn into the plunger cylinder 15 from the bottom of the chamber 14, the oil moving through the sleeve 20, valve chamber 17, and con-duit connection or passage 1S. Under such action the fluid in the chamber 19 is lowered, and filling of the unoccupied portion of the plunger cylinder 15` by reason of the elevation of the piston or plunger 27, takes place.

lVhen the chassis and the body of the vehicle move upwardly on what is generally termed the recovering movement or rebound, the casing 13 will move upwardly with the chassis or body, the free end of the crank or actuating lever 35 being restrained from upward movement due to the fact that it is connected by the webbing 37 with the axle 12. rlhis causes the crank or actuating lever 35 to gradually assume a horizontal position, or a less inclined or angular position, and at times an oppositely-inclined or Langular position, depending, in the first instance, lonthe position of such lever when the partsfare normal; Howeveigaslshownin the drawings, thecranli or actuating lever 35 in substantially horizontal' position when the .par sareA normal, andconsequently after as- -the` siherical orf ball valve 22 was seated against' its valve seatl under action ofthe. spring QSVthe'instant the piston reached the endofIl its upward movement, the oil forced into saidivalve chamber by: action of the piston or plunger 27 will be compelledlto find an outletl` froml the valve' chamber through the' exposed' inner end portion of the elongatedopening ori-slot 43' formed in the valve' sleevef, tlieoillpassing' into said sleeve and entering the' chamber` le" under retarded'flow through the exposed portion of said elongatedfopenin'g'or slot.y

The elongatedlopening orf slot is caused to bev restrictedby the spring` 57 within the ad justing screw 46.this spring holding the collar 53 oni the valvel.` againstthe'endof the valve sleeve` The exposed portion of the opening: or sloti 43 is the normally effective portion of said'opening orlslouand in order to 4enlarge this effective portion, `the pressure agaiust the' yinner-end ofthe valve 51S must be suflicien'tto'overcome thetensionof the spring 57-,vwhich tensionmay4 beincreased or diminished to suitthe conditions existing when the shockabsorber is applied to `any particularl automobile.. L

If., at? any time, the' pressure created by the action: of the pistonorplunger 27 against the* oil? within the'piston cylinder and valve chamber eirceecsthatr ofthe force of the springt?, the' valve 5l will'be moved outwardly and cause' theeiiiectiveportion of the openin'glor slot a'inthet valve sleeve to be enlarged@ in size inf accordance with the increased pressure appliedy toy said valve. it will thus lie-apparent that the escape ofthe oilrfrom the piston cvlinder into'the chamben lfiis restricted and -controlledfor governed after-'the pressure reaches-a certain degree in exact proportion to the'pressure appliedg' it beine; understoodthat the normally effective opening in said valve `sleeve will properly take care of'allpressuresfup.to that required to bringt-he valve 5l. into action. rlhis assures afslow even recovery of the automobile body on its rebound without checks or stops,

asappears common in present .day fluid shock absorbers, generally referredto as hydraulic shock absorbers.

By using an elongated opening. or slot to serve as the oilpassage leading'to'the.' oil chamber 11i andiproviding means forgradually opening saidelongated opening orfslot under pressure created by the plunger,4 a' gradual movement of the automobile' bodyfis assured, the body moving downwardly' under shock without any intermittent checks or points of retardation in its movement, as occurs with shockl absorbers now in use.4

The outward movement of the valve 51 iscontrolled by the inner endofA the.` gland i5 and it is therefore essential that the disk iortion' 55 of the collarl 53 be of af diameter somewhat greater than the threaded open# ing in said gland, but smaller than' the `opening lliY in the casing, so thatl the marginal portionl of this collar will come in contact with the end ofsaid gland at the limit of` the outward movement of the'valve, as indi-v cated'by dotted'linosin'Fig; 6, whiclrshows themaximum effect-ive enlargementof the opening or slot lin the valve sleeve.`

As there is a tendency ofv theoilwitliin shock absorbers-of this type creating a frothy or foamy condition at the top of'theoil withiny the plunger cylinder, the initial downward movement of the plunger upon the recovering or rebound stroke thereof is' ineffective' when this condition becoinesag-r gravated, due to the fact that theI froth' causedfby agitation ofthe oil, offers no rcsistance to the downward movement of the plunger, and this plunger is consequently free in its downward movement until it comesiin contact with the oil body within the cylinder. This results in the parts between theplunger and the axle of the automobile having free and unrestrained movement and when the automobile body is depressedV in passing over a rut or elevation on the road, or' through a depression, the body is offered no resistance in its upward movement during the time that the plunger is con'ipell'ed to pass through the frothy or foamy upper portion of the oil within the cylinder. Therefore, the initiall portionof the recovering or reboundA movement of the body will be unrestrained and no check offeredithereagainst until the plunger comes in contact with the oil body, when a sudden and abrupt check is offered tothe upward movement until a portion of this oil body is being'forced out through the restricting op'enin'g43. therefore provide means to preventv the formation ofl froth at the top of the. oil body within the cylinder,l or at least to minimize such formation, and if under' severe conditions some froth or foam is createdat' such point, to permit the frothy or foamy oil surface portion to escape from beneath the plunger, andto this end a shaluio los

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low and comparatively narrow groove 27a is formed in the plunger 27 from end to end thereof, which allows oil, or any frothy or foamy matter forming at the top of the oil body in thc cylinder, to pass upwardly through the groove and escape into the oil chamber A, thus assuring resistance at every point of the recovery or rebound movement of the automobile body.

rlhe modilication shown in Fig. 7 is similar to that of the preferred construction in the preceding figures, with the exception that the outward movement of the collar 53 is limited by an adjustable stop disk 58 arranged within the opening let formed in the valve casing. 1n this construction the opening la is somewhat longer than that in the preferred construction, and it is screw threaded along its entire length, thus permitting the adjusting disk 58 to be moved along a range extending from the inner end of the gland l5 to the inner end of the opening la into which the gland is threaded.

1n the modification shown in Fig. 8, the adjusting screw is dispensed with and the gland, designated by the numeral 59 in this case, is somewhat modified in construction in that it has a bore 60 extending from its inner end outwardly, and this bore receives the spring 57, the outer end of the gland being, of course, closed, as at 61, to provide an abutting wall for the outer end of said spring, the inner end of the spring bearing against the collar 53 of the valve, as in the preferred construction. The inner end of this gland limits the outward movement of the valve 51 within its valve sleeve, and determines the range of movement of said valve. In this instance, a gasket or gaskets 62 are interposed between the casing, and a shoulder 63 formed on the gland. No adjustment for changing the tension of the spring is provided in this construction, but it is intended that the spring shall have minimum pressure against the collar of the valve when the parts are assembled, and if found that the pressure so provided is insullicient for effective operation of the shock absorber, the gland 59 is removed and one or more washers or similar disk-like elements placed within the bore so as to bear against the closed outer-end walls 61 of the gland, in which case the outer end of the spring will bear against these washers or other elements instead of against said wall.

ln the modilication shown in Fig. 9, the opening la formed in the casing 18 is screwthreaded from end to end, and the gland 64 threaded thereinto has its bore 65 screwthreaded from its outer end inwardly for a short distance, as at G6. A screw plug 67 is threaded into the screw-threaded portion of this bore and behind it is arranged a packing washer 68 which may bear directly against the inner end of the plug 67, or have any number of metallic disks, such as 69 associated therewith, either against t-he inner side of the packing washer 68 or between said washer rc. the plug; the latter, for example, being il .istrated in Fin'. 9. rl`his metallic washer comprises two thin metallic members 70, 71, and a member 72 compressible between said thin metalic members. Vllhe intermediate member 72, upon being compressed, will cause expansion thereof radially so that it is forced against the wall of the gland 64 behind the plug 67 and renders the bore of said gland oil-tight at this point. The spiral spring 57 bears against the packing washer 68 when used without disks, such as 69, or when used with disks located between the washer and the plug, or the spring may bear against the disks when placed behind the washer. The spring 57 acts against the valve 51 in the same manner as illustrated in the preceding figures, and the tension of this spring is varied according to the absence of the disks 69, or to the number of suoli disks employed.

Having thus described my invention, what 1 claim is 1. A shock absorber, comprising a casing having a chamber containing oil and a cylinder also containing oil and separated from said chamber by a wall, and a plunger within said cylinder, said chamber and cylinder having conduit connection with each other controlled to admit the free iow of oil from said chamber to said cylinder upon the suction stroke of said plunger and to restrict the flow of oil from said cylinder to said chamber through a passage having a normally effective open area enlargable upon the pressure stroke of said plunger causing a predetermined high pressure within said cylinder and in exact accordance with the increase in pressure.

2. A shock absorber, comprising a casing having a chamber containing oil and a cylin der also containing oil and separated from said chamber by a wall, said wall having a valve chamber projecting into said oil-containing chamber, a plunger within said cylinder, a valve within said valve chamber normally closed and adapted to open upon the suction stroke of said plunger to admit the free passage of oil from said oil-containing chamber to said cylinder, a sleeve projecting from said valve chamber and extending into saidoil-containingcha1nber,saidsleevehaving .conduit connection with said cylinder through said valve chamber and having also an elongated longitudinally-disposed opening in its peripheral wall of even width throughout its effective length, and a valve within said sleeve controlling said opening to gradually open the same according to pressure exerted upon said valve.

8. A shock absorber, comprising a casing having a chamber containing oil and a cylinder .also containing oil and separated from saidichainber by a'fwall, a'plunger within said cylinder, a valve chamber projecting into said oilcontaining .chamber .from said wall and having conduit connection with said cylinder and having also a valve-coiitrolled passage for the -freepassage of oil from said oil-containing chamber to said cylinder upon the suction stroleof said plunger, a sleeve extending ltrom-the wallet said valve chamber intoisaid oilecontaining ch amber and having an elongated longitudinally Idisposed outlet openingin its peripheral wall,ia valveiitting intosaid sleeve and having a collar bearing against the `outer end :thereof to limit the inward movement of said valve and normally maintain said oil-containing chamberin com munication lwith said valve chamberthrough a,given area of said opening, a coil spring bearing againsttlie colla-not said valve to hold said 4.collar against said sleeve, said spring yieldingunder abnormallpressure applied to saidvalveand said valve being movable under suclrpressure inexact accordance with the,pressure.toiopen saidoutlet opening to a corresponding degree, and anadjustable element'threaded-into said casing to vary the tension ot said coil spring.

4. A shockabsorberycomprising a casing liavinga chamber'containing-.oil .andl a cylinder `also containing oil and separated from said chamber by a wall, a plunger within said cylinder, Vsaid wall i having a hollow portion projectingtherefrom near its lower end and-provided witha passage leadingto said cylinder andra passage 'leading downwardly to .-said eil-containing chamber, a springpressed valve within said 'hollow portion controlling Ythe 'passage `downwardly Atherefroinand Aadapted itoopen for the treepassage ot oil Vfrom said chamber-to said cylinder upon the suction stroke ot said plunger, a sleeve in communication wth said hollow portion and extending outwardly therefrom, said sleeve `having a slot `formed lengthwise in its peripheral wall, a member extending into said sleeve and closing a portion of said slot, said member having a collarvatits outer end bearing against the outer end of said sleeve, the .inner lend ,ot said member terminating a predetermined distance trointhe inyner end of Isaid slot, .an opening in said casing alined with said member, a gland threaded ,into said opening yand against each inner 'endroit whiclrthe collar ofsaid member justine` screw and extending vtheretrom with its ,inner end in Contact with the collar of said member, said spring liavingitsfouter end incontact. withpthe inner end `and wall ot said bore.

quantities ot oil `therethrough in exact proportion fto thepressure exerted on said .valve and to ypermit gradual increase :in the Iiiow oioil ythrough said slot.

16. .ln ashoclrabsorber, anoil control l,device, comprising .a passage rhaving .a :surrounding ivall provided vwith -an elongated slot extending.longitudinally along-said wallA and through which passage oil under -pressure to be passed, a valve movable within said ipassage `and normally leaving a predetermined restrictingarea of said slot Open to ,permit limited quantities of oil `to ,pass a through said slot under all degrees below said predetermined pressure, `and .means to force .oil into said passage under fpressure fto increase the etlectiveopened.areaot said slot in accordance with .the increase in pressure s and topermit gradual increaseiin the rtlowof oil through said opening.

.'7. In a shock absorber,.an oil,pressure,control device,eomprisinga passage having an elongated opening througlithe Wall ,thereof through which controlled .variable Ailowot oil yis passed, andan elementmovablein the direction .oit thelength Aof said'opening subjected .to the gpressure ofthe oil wthinsaid passage and serving toopen said opening .to v;

a greateiwor lesser degree .and in exact ,accoi-dance Vwith the degree `of .pressure .of the oil acting against said element and to permit gradual increase or reductionin the'iiow of eil through said opening, depending on the direction or movement off said movable element. y

8. ln a shoclrabsorber, apressure oil control device, comprising a passage having an elongated opening in the wall thereof` of coinparatively small crosswise dimension and through which oil under variable pressureis to be passed, an-element within said passage movable in contact with the wall thereof to Close the maior portion-ot said opening and held to normally leave a predetermined restricting area ot said opening uncovered thereby tope-rmit limited quantities of oil to pass through said opening under all degrees below a predetermined pressure, means to hold said element in normal position Vand yieldable to permit movement of said element along said opening as the 'pressure against said element increases beyond said predetermined pressure, .said element tui- CII ther uncovering said opening to increasing extent in proportion to the pressure applied to said element and to permit gradual increase in the flow ot oil through said opening.

9. A shock absorber, comprising a casing having a chamber containing oil and a cylinder also containing oil and separated trom said chamber by a wall, a plunger withi said cylinder, said wall having a passage leading from said chamber to said cylinder for the free flow of oil from said chamber to said cylinder upon the suction stroke of said plunger and a passage leading from said cylinder and having an elongated opening ot even width throughout leading to said chamber, said opening being normally restricted to a given size and capable ot feeding oil trom said cylinder to said chamber under pressure exerted by said plunger, and means to regulate the flow of oil through said passage by gradual enlargement of said opening so as to provide gradual resistance relietl without points of resistance;

l0. A shock absorber, comprising a casing having a chamber containing oil and a cylinder also containing oil and separated "from said chamber by a Wall, a plunger within said cylinder, means to allow the l'ree flow ot oil from said chamber to said cylinder upon movement of said plunger in one diret-tion, and means to control the iow ot oil from said cylinder to said chamber, including a sleeve projecting` from said wall and in communication with said cylinder, said sleeve extending into said Chamber and having an elongated longitudinally-disposed opening' in its wall, and a valve located within said sleeve to control the passage ot oil through said elongated opening, said valve being springretained within said sleeve and being movable outwardly under pressure exerted by said plunger when moving in an opposite direction, the outward movement ot said valve causing a gradual opening of said elongated longitudinally-disposed opening to permit a gradual increase in the How of oil therethrough in exact proportion to the pressure exerted against said valve by said plunger.

1l. A shock absorber, compri-sing a casing having a chamber containing oil and a cylinder also containing oil and separated from said chamber by a wall, a plunger within said cylinder, said wall having two passages between said chamber and said cylinder c trollcd to admit the free flow ot oil from said Chamber to said cylinder upon the suction stroke ot said plunger and to assure a restricted flow of the oil from said cylinder to said chamber upon the pressure stroke of said plunger, and means normally restricting the passage controlling the iow of oil from said cylinder to said chamber to a given size operable only when the pressure exertedv by said plunger reaches a predetermined point to provide a gradual enlargement ot said passage under increasing pressure and to cause a gradual increase in the flow ot oil therethrough in exact proportion to the pressure exerted against said restricting means.

l2. A shock absorber, comprising a casing having a. chamber containing oil and a cylinder also containing oil and separated from said chamber by a wall, a plunger within said cylinder, said wall having two passages between said chamber and said cylinder, one passage being controlled to admit the free iiow of oil from said chamber to said cylinder upon the suction stroke of said plunger and the other having a normally restricted passage for the flow of oil from said cylinder to said chamber upon the pressure stroke of said plunger, said,normally-restricted passage being increased in size under pressure o'l' said plunger above a predetermined point in exact accordance with the increase in pressure to permit a gradual increase in the flow of oil therethrough, also in exact proportion to the pressure applied.

18. A. shock absorber, comprising a casing having a chamber containing oil and a cyl- Linder also containing oil and separated from said chamber by a wall, a plunger within said cylinder, said wall having two passages therein, one to a admit the tree tlow of oil trom said chamber to said cylinder upon the suction stroke ot said plunger and the other normally restricted to a given size and controlling the flow of oil trom said cylinder to said chamber, and spring-pressed means determining the given size ot said last-mentioned and movable under pressure of said plunger beyond a given point to enlarge said passage in exact accordance with the increase in pressure and to assure a gradual increase in the iiow of oil through said passage, also in exact proportion to the pressure exerted against said spring-pressed means.

le. A shock absorber, comprising a casing having a chamber containing` oil and a cylinder also containing oil and separated from said chamber by a wall. a plunger within said cylinder, said wall having a passage between said chamber and said cylinder controlled to admit the tree flow of oil from said chamber to said cylinder and a passage tor the restricted flow of oil 'from said cylinder to said chamber upon the pressure stroke et said plunger, said last-mentioned passage having .a normally eiilective outlet into said chamber ot a given area. and a movable element within said passage adapted to increase the area ot said outlet when the pressure ot the oil against said element reaches a predetermined high point, the increase of area ot said passage being in exact accordance with the increase in pressure and the increase in flow ot oil through said passage being also in exact accordance with the increasing pressure.

iso

vl5. `A shoelrabsorber, compri-sing acasing having `achamber containing oil and acylinder also containing oil and separated from saidehainber by a wall, .aplunger within said cylinder, lsaid wall having a passage between saidchamberand said cylinder controlled to udinit'tlie `free flow ofoil `from said chamber to said cylinder and a passage for the restrictedzilow of oil :from said cylinder tosaid chamber .upon the pressure stroke of said plunger, 'said l last-mentioned passa-ge having anelongated outlet into said chamber 4of an vmovable 4`:element to cause lit to recover itsl normal vposition when the `pressure thereaga-inst :is lowered to or below .said predetermined high point, and means to increase ,or lvdiminish lthe pressure exerted by said yielding mean-s .against `said movable element.

.16. shock absorber, Acomprising a easing having a chamber containing oil and a cylinderalsocontaining oil and separated from said chamber by `a wall, a plunger Within said cylinder, said wall-having `two passages between said lchamber and said cylinder, one ot' said passagesin'eluding a sleeve projecting into said voil-containing .chamber and having a-slet of even widthextending lengthwise along its wall, anopening in said casing alined 'with said sleeve, a stop device arranged within said-opening,a valve normally positioned within said sleeve and terminating at its-inner end a distance from the inner end of said slot to provide a restricted opening ltlnough said sleeveatthe inner end of aid slot, .and yielding means exerting pressure again-st said valve to maintain the same in normalpesition, said yielding means permitting said valve to move outwardly so t-o-nncover a .greater portion of said slot under and in exact vaccordance with the increased pressure oit1 the oil within said sleeve andto permit a `gradual increase in the flow of oil from `said cylinder to said chamber in .exact vproportion to the pressure of the oil within saidsleeve.

.17.111 a 4shock absorber, an oil control device comprising a. sleeve forming part of a passage and having an elongated slot eiltending longitudinally alongits wall, a Cylindrical valve provided with anabutment bearing against the outer end of said sleeve ton'ormally leave .uncovered alpredetermined restricting area oij said slot, said valve being maximum degree of openingof'said'slot, fa

spring normally holding `said :abutment against the-end of said sleeve, andfmeansito regulate the tension of said spring.

ln testimony whereof, lf-aiiix inv-signature.

.Anornn W. r. MANZEL. 

